Rationale and Research Questions

Marine mammal and sea turtle strandings can be unusual events or indicators of problems in our ocean ecosystems. Seeing patterns in the strandings of marine mammals and sea turtles can be indicative of more complex issues that may not be transparent. Some example of these issues could be viral outbreaks in lower trophic level populations or toxic algal blooms that kill off all sea life in the area. Because humans demand and consume seafood, understanding the problems that arise are essential to preventing the consumption of contaminated seafood along with the management of fisheries. By studying marine mammal and sea turtle strandings, we get insight on the health of our oceans.

Our objective is to analyze animal strandings over the years to see if there any trends in the quantity of strandings for each family (cetaceans, odontocetes, mysticetes, and pinnipeds). We have decided to look at the total number of strandings per year for all families, the changes in strandings over the years for each family and the seasonality differences across all years for each family.

Dataset Information

The dataset that we chose to work on is the Mystic Aquarium’s marine mammal and sea turtle stranding data from 1976 to 2011. It contains the number of whale (odontocetes and mysticetes), dolphin, and sea turtle strandings that occurred along the coasts of Connecticut, Rhode Island and Fishers Island, New York, USA. The latitude ranged from 41.00 to 41.86 while the longitude was from -73.65 to -71.10. Within the dataset, there are a total of 1,141 strandings, of which 885 were marine mammals and 256 were sea turtles. We data was provided using the datum WGS: 1984 and we performed a data transformation into UTM 19 (32619).

Mystic Aquarium’s marine mammal and sea turtle stranding data 1976-2011

Contains whales, dolphins, and sea turtles
Number of different species in each family
Only one stranding record from 1976, the rest start at 1990, so that 1976 record was excluded from analysis
Coordinate system: WGS 1984
Transformed to UTM Zone 19 for geospatial analysis
Data Wrangling
- Selected for data columns we wanted to parse down dataset
- Reformatted the date
- Wrangled data to include a family column for each animal group (mysticetes, odontocetes, pinnipeds, and turtles)
- Further wrangling was conducted to determine and isolate yearly and monthly stranding totals

colnames(Strandings)

##  [1] "dataset_id"      "row_id"          "latitude"        "longitude"      
##  [5] "species_name"    "scientific_name" "common_name"     "itis_tsn"       
##  [9] "group_size"      "series_id"       "date_time"       "timezone"       
## [13] "ds_type"         "platform"        "provider"        "lprecision"     
## [17] "tprecision"      "oceano"          "notes"           "last_mod"

colnames(Strandings_Final)

## [1] "Family"       "common_name"  "species_name" "Date"         "Year"        
## [6] "Month"        "latitude"     "longitude"

head(Strandings_Final)

head(Annual_Strandings_Totals)

head(Monthly_Strandings_Totals)

Exploratory Analysis

Flow between text and visualizations is cohesive
Relevant exploratory information is visualized

Analysis

Flow between text and visualizations is cohesive
Visualizations and statistical tests pertain directly to specific questions
Statistical results are reported in plain language with relevant statistical output in parentheses
Findings are reported clearly in relation to research questions

Pinnipeds:

Question 1: Are there years or months where the number of pinniped strandings are significantly different?

Question 2: Are there trends in pinniped strandings based off of this dataset?

Whales:

Question 1: Are there years or months where the number of toothed whales (odontocetes) strandings are significantly different?

Question 2: Are there trends in toothed whale (odontocetes) strandings based off of this dataset?

Question 3: Are there years or months where the number of baleen whales (mysticetes) strandings are significantly different?

Question 4: Are there trends in baleen whale (mysticetes) strandings based off of this dataset?

Turtles:

Question 1: Are there years or months where the number of turtle strandings are significantly different?

Question 2: Are there trends in turtle strandings based off of this dataset?

Summary and Conclusions

Major findings are summarized
Conclusions relate back to the original research context

$Deceased Fin Whale - Joshua Meza-Fidalgo, 2020$

Deceased Fin Whale - Joshua Meza-Fidalgo, 2020

References

Data: https://seamap.env.duke.edu/dataset/945

Halpin, P.N., A.J. Read, E. Fujioka, B.D. Best, B. Donnelly, L.J. Hazen, C. Kot, K. Urian, E. LaBrecque, A. Dimatteo, J. Cleary, C. Good, L.B. Crowder, and K.D. Hyrenbach. 2009. OBIS-SEAMAP: The world data center for marine mammal, sea bird, and sea turtle distributions. Oceanography. 22(2):104-115.
Smith, A. 2014. Mystic Aquarium’s marine mammal and sea turtle stranding data 1976-2011. Data downloaded from OBIS-SEAMAP (http://seamap.env.duke.edu/dataset/945) on 2022-04-02.

Photos: Special thanks to Joshua Meza-Fidalgo for providing whale photos for us to use.

Marine Mammal and Sea Turtle Stranding Analysis